The present invention relates to a keypad for an electronic device and to an electronic device incorporating the keypad. In particular, the electronic device to which this invention relates is a mobile communication device such as a telephone but it could also be any other type of electronic device that incorporates a keypad including, for example, a personal data assistant (PDA) or a television/stereo remote control unit.
A conventional mobile telephone includes a plurality of buttons or keys having numbers and other symbols printed thereon to designate the function that each key performs when pressed. For example, the keys bearing the numbers 0 to 9 can be used to input a telephone number into the telephone. These keys protrude through apertures in the housing of the mobile telephone and are spaced from each other and give the appearance that each key is a separate component. However, the keys are all integrally moulded in one piece of flexible material such as rubber and extend from the surface of a flat sheet mounted on the electric circuitry inside the telephone housing. The moulded component forming the desired arrangement of keys is known as a keypad or key-mat. Typical keypads of the type described are known from U.S. D421,019 and U.S. Pat. No. 5,940,015.
It will be apparent that the majority of all known keypads are constructed with a space between each key. As the keypads are made in a moulding process, the distance between each key often represents the minimum distance achievable due to the thickness of the wall between the keys in the mould which cannot be reduced below a minimum otherwise the mould will fail. However, owing to design considerations and in attempts to reduce the size of mobile telephones to a minimum, it has now become desirable to manufacture keypads having keys that are positioned much closer together than is possible with the conventional moulding technique. In some applications, it is also desirable to position the keys so that their edges wholly or partially abut each other so that the sides of the keys are in physical contact or are contiguous.
To date, the above requirement has been met by moulding the keys separately and then individually gluing or otherwise attaching them in the required close proximity onto a flat sheet to form the keypad. However, it will be readily appreciated that this is a time consuming laborious process and it becomes very expensive and complicated especially when a large quantity of keypads are to be manufactured. U.S. Pat. No. 5,546,457 discloses a conventional keypad made using this technique.
According to the present invention, there is provided a keypad for an electronic device comprising a plurality of splayed fingers, a plurality of keys on each finger wherein the fingers adopt a non-splayed configuration when the keypad is installed in said electronic device such that a key on at least one finger is positioned in close proximity to a key on an adjacent finger.
The keypad of the present invention is moulded using the conventional technique using a mould having a different shape. The wall of the mould between the keys is maintained at or above the minimum thickness required. Once the keypad is removed from the mould, the keys are positioned a distance apart that is less than the minimum wall thickness of a conventional mould by moving the splayed fingers together and maintaining them together when the keypad is installed in the electronic device.
In one embodiment, a key on at least one finger is contiguous with at least one key on an adjacent finger when the fingers adopt the non-splayed configuration.
Preferably, the keypad adopts the splayed open configuration when unconstrained, the fingers being constrained in the non-splayed configuration when the keypad is installed in said electronic device.
In a preferred embodiment, the keypad is a unitary component.
In one embodiment, each finger has a zigzag configuration along its edge where it contacts an adjacent finger when in the non-splayed configuration.
Preferably, at least one key on each finger extends to at least one edge of said finger where it contacts an adjacent finger when in the non-splayed configuration.
Preferably, there is an aperture in the keypad in the crook between a pair of fingers. This aperture prevents the material between the fingers joining them together from breaking as a result of the material splitting. It also prevents this area of the keypad from buckling when the fingers are in the non-splayed configuration.
In another embodiment, co-operating means are provided on two adjacent fingers to hold them in the non-splayed configuration.
Preferably, the co-operating means comprises a tongue on one finger and aperture on an adjacent finger through which the tongue extends in the non-splayed configuration.
The invention also provides an electronic device including a keypad according to the invention, wherein two or more keys protrude through a single aperture in the casing.
Preferably, said two or more keys are formed in a row and, most preferably, a number of rows extend through a corresponding number of openings in the casing.
According to the invention, there is also provided a method of installing a keypad in an electronic device according to any preceding claim, including the steps of:
a) taking the keypad having a plurality of splayed fingers from a mould;
b) moving the fingers together to form a non-splayed configuration;
c) mounting the keypad to the electronic device such that the fingers are retained in said non-splayed configuration.